A golf ball generally comprises a one-piece construction or it may include several layers including a core and an outer cover surrounding the core. Typically, one or more layers of paint and/or clearcoat are applied to the exterior surface of the golf ball In one typical design, the exterior surface of the golf ball is first painted with at least one pigmented primer and/or basecoat followed by the application of a clear top coat. The basecoat and/or primer and clear topcoat are applied to the golf ball to enhance the aesthetic appearance of the ball as well as mask or cover surface blemishes that may have resulted from the manufacturing process. The clear top coat is particularly important, in that the coat protects any images, that is, trademarks, logos, or other markings that may be placed on the exterior surface of the golf ball. Customized golf balls contain an image such as a logo for a University or a company (other than the golf ball manufacturer) on the exterior surface of the clear coat.
Depending on the ink formulations used in depositing the images and the formulation of the clear topcoat, the adhesion between the image and the clear topcoat can fail. This is particularly so with images on the exterior surface of the clear coat. Failure is visually noticed by cracking or chipping of the image after repeated hits with a golf club.
Current clear topcoats are polyurethane polyols, usually poly(ester-urethane) polyols crosslinked with a polyisocyanate. To provide for enhanced mar and abrasion resistance, a so-called slip agent is included in the polyurethane coating formulation. It is believed that these slip agents can adversely affect the adhesion of the topcoat to the images, particularly the images on the exterior surface of the clear coat. To overcome these adhesion problems, an adhesion-promoting agent can be added to the formulations. However, many adhesion-promoting compounds are not effective.